Technical Abstract: Emerald ash borer (EAB) Agrilus planipennis Fairmaire (Coleoptera: Buprestidae), is an invasive beetle species from Asia that has caused extensive mortality of ash trees (Fraxinus spp.) since arriving in the U.S. in 2002. Especially hard hit are green ash (F. pennsylvanica), black ash (F. nigra), and white ash (F. americana). Since its detection in the Detroit area, the beetles have rapidly spread throughout Michigan and into portions of Illinois, Indiana, Ohio, Pennsylvania, Maryland, West Virginia, and Ontario, Canada. EAB detection methods, especially in low infestation areas, relied heavily on visual surveys and the use of girdled trap trees to detect the presence of the beetles. Both methods are labor intensive and relatively expensive, and improved methods of beetle detection are urgently needed. Semiochemical baited traps for monitoring EAB are currently under development. Pheromones have been used to detect pest insects, but none have so far been identified in the Buprestidae. We have identified a predominately female-produced macrocyclic lactone, (3Z)-dodecen-12-olide, that could serve as a pheromone in EAB. The behavioral effects of this lactone will be discussed. Girdled green ash trees have an elevated release of volatile bark sesquiterpenes compared to ungirdled trees, and GC-EAD studies showed six antennally active sesquiterpenes for both male and female EAB. Five of these six compounds were identified as a-cubebene, a-copaene, 7-epi-sesquithujene, trans-ß-caryophyllene, and a-humulene. At NCAUR, GC-EAD studies with white ash bark volatiles showed two active sesquiterpenes, 7-epi-sesquithujene and previously unidentified (-)-eremophilene. The key isolation procedure for the two compounds was silver nitrate/silica HPLC. Identification was by GC-MS, NMR, polarimetry, and micro-chemical reactions. The essential oil of the Manuka tree (Leptospermum scoparium) contains many different volatile compounds including five of identified sesquiterpenes with the exception of 7-epi-sesquithujene. Similarly, the oil from the Brazilian walnut tree, Phoebe porosa, contains at least five of the identified compounds. Sticky traps baited with either Manuka or Phoebe oil have been shown to attract male and female EAB in the field. Isolation and purification methods are being developed to obtain field bait quantities of (-)-eremophilene from Buddah wood (Eremophila mitchelli) oil; and the behavior effects of this compound and others will be discussed in light of an effective semiochemical-based monitoring system for EAB.